1. Early Theories of Genetics

2. Early Theories of Genetics
Aristotle proposed the Theory of Pangenesis
“Pangenes” come from all over body
Changes in body during life can be passed on
Idea later adopted by Lamarck and Darwin

3. Early Theories of Genetics
Aton van Leeuwenhoek proposed the Homunculus Theory
“Homunculus” is a miniature being in sperm cells
The mother serves only as an incubator
All characteristics are inherited from the male
He and his followers were called “spermists”

4. Early Theories of Genetics
Regnier de Graaf was the first person to describe the ovarian follicle where egg cells are produced
The egg contains an entire organism in miniature and that semen only stimulates its growth
All characteristics are thus inherited from the mother
de Graaf and his followers were called “ovists”

5. Early Theories of Genetics
Jean-Baptiste Lamarck proposed that organisms could past on traits they aqquired during life
This was an explanation of how organisms became adapted to an environment
The idea influenced Darwin

6. Early Theories of Genetics
Nineteenth Century Scientists realized that both parents contribute to the characteristics of offspring.
The "blending" theory then became the favored explanation of inheritance.
Hereditary materials from male and female parents mix to form the offspring, and once blended, the hereditary material is inseparable
Since the hereditary material is inseparable, the population should reach a uniform appearance after many generations.

7. Gregor Mendel Born 1822 Monk at 21 Priest at 25 Studied Math & Science
at University of Vienna

8. Gregor Mendel 14 years teaching HS Math &Science
Grew food gardens for monastery
Experimented with Pea Plants
Applied Mathematics to Genetics

9. Gregor Mendel He cross-pollinated “true-breeding” pea plants
He worked with seven different traits.
Each experiment would take three years
He called the parent plants P
The second generation F1
The third generation F2

10. Gregor Mendel He found that some characteristics hide others.
He found that these hidden traits would reappear in later generations
He found mathematical ratios in each generation
He called those genes that would hide others - Dominate “T”
Those genes that could be hidden he called - Recessive “t”

11. Gregor Mendel
He realized that genes weren’t “blended”, that they were particles that were passed on to each generation from each parent
He didn’t know where the genes were or what they were made of
His work was published in a Czech Gardening Journal and it wasn’t noticed

12. Gregor Mendel 1920-30s his work was “discovered”
It was repeated and became the basis of modern genetics
He is know as “The Father of Genetics”